General Motors’ car sales may be cooling, but when it comes to trucks, the company can’t build ‘em quickly enough. And it’s been the special editions and upgraded models that have really fueled truck sales across GM’s lines — there are more than a dozen trims and special editions for Chevrolet’s full-size trucks.
But Chevy certainly hasn’t put its midsize Colorado on the back burner. The General has rolled out special editions of the Colorado at a consistent pace since relaunching the truck back in 2015. That very first year, buyers could get a special Z71 Trail Boss model. A year later, Chevy added a Midnight Edition, as well as the Shoreline model. In 2017 Chevy made big news with its off-road-focused ZR2 and followed it with Midnight and Dusk versions.
For 2019, Chevy’s small truck game is only getting stronger with three new special editions: a sporty RST variant, a Z71 Trail Runner that adds the tires and protection from the ZR2 and the heartiest of the bunch, the new Colorado ZR2 Bison.
The Bison marks GM’s first collaboration with aftermarket tuner American Expedition Vehicles, or AEV. AEV has been churning out expertly built Jeeps and Ram trucks for more than 20 years, including perhaps its most famous model, the Brute. That was an AEV-designed and -built Jeep Wrangler pickup truck that arrived years before Jeep’s own recently introduced Gladiator pickup. And if we’re honest, the success of the Brute probably gave Jeep the encouragement to build its own.
The name “Bison” comes from both AEV’s logo (a bison), as well as GM’s ownership of the name. The original GM Bison was a wild prototype gas-turbine semi-tractor trailer built for the 1964 World’s Fair. In the ‘70s and ‘80s, Chevrolet used the Bison nameplate on a production heavy-duty Class 8 truck. And now, more than 30 years later, it’s a special edition pickup.
The Bison package was in development by AEV for the past two and a half years. Mechanically, it doesn’t stray too far from the ZR2 Colorado. Like the regular ZR2, Chevy makes both cab configurations available for the Bison, as well as a choice of either gas or diesel engines. AEV doesn’t modify the suspension of the ZR2, so the factory 2-inch lift and sophisticated Multimatic Dynamic Suspension Spool Valve, or DSSV, dampers remain in place, as do the stock-size 265/65R-17 Goodyear Wrangler Dura Trac tires.
What AEV does add is heavy-duty protection. That means beefy stamped steel bumpers along with sliders and skid plates to fully armor the truck’s underbelly. Now, the Bison is built on the same factory production line as standard-issue Colorado ZR2s, so the fitment flaws found in typical aftermarket parts just wouldn’t do. But AEV is meticulous about how its parts fit, which gave GM the confidence to produce the Bison right in its own factory.
“It’s a huge step to be involved with an OE in the plant," says AEV President Dave Harriton. “But we do things OE style. We perform thermal and corrosion testing. And the bumpers don’t affect the cooling for either engine.”
Harriton says that curbing weight gain from the added components was one of their biggest hurdles. Traditional steel used in the aftermarket is heavy, and if AEV were to build all the armor with this steel, the Bison would be over Chevrolet’s target weight. So his team uses hot-stamped boron steel. He says the AEV boron steel units can be up around four times lighter than a comparable steel part. And according to Harriton, these skidplates are more resistant to gauging and have a very high yield strength, so they absorb hits and spring back.
AEV designed five new skidplates from this material that shield the oil pan, fuel tank, transfer case and both differentials. Above the belt, the new steel bumpers are handsome and built for those who really take their vehicles off-road. The front unit has been designed to accept an aftermarket electric winch and has detachable “wings” for additional tire clearance. The rear bumper incorporates additional departure angle protection at the corners, as well as built-in recovery attachment points and even cut-outs for more lighting.
New wheel flares provide a bit more tire coverage and give the Bison some imposing shoulders. The AEV package includes a handsome new wheel design too. The stock 31-inch tire size is maintained so the truck didn’t require new emissions testing. But the big flares do create more room in the wheel wells … and we hear that a 33-inch-tall tire could fit with a little trimming of the plastic.
AEV is a big believer in snorkels, and it’s not just for water fording. Follow a convoy on any 4WD adventure, and unless the terrain is muddy or rain-soaked, it’s very likely that plumes of thick dust will get kicked up and surround every vehicle. In a short time, air cleaners can clog. So AEV makes a snorkel available for the Bison with a prefilter system located high up to help find cleaner air. Harriton says the snorkel is polarizing for some buyers, so it’s available as an extra-cost option at the dealership.
The Execution
The Bison certainly looks the part. The new bumpers, flares and wheels add to the already purposeful modifications Chevy made when it created the ZR2. Take a long slow walk around the new truck and it’s not only a tough-looking machine, but you can see how nicely the parts fit together. It’s clear this would be an excellent truck to use for an overlanding expedition.
But here’s the thing about the Bison. While the $5,750 package might not actually improve the truck’s off-road capability per se, the added protection lets you tackle tough terrain with less fear of body damage. And if you’re going to take a near-$50,000 truck off-road, you’ll want to keep it relatively scar-free.
We recently had a chance to drive the Bison on some of the famous hardcore rock-crawling trails near Florence Junction, Arizona. This boulder-strewn stretch of rugged terrain is no place for the average stock 4X4.
But the ZR2 isn’t the average 4X4. As soon as we hit the dirt, we begin playing with the ZR2 Bison’s lockers and 4WD system. In 4WD high range, we easily cruise the dirt two-track that led to the more serious rocks. The ZR2’s increased wheel travel is noticeable — especially up front, where even big dips in the road don’t wash out the front end.
It’s certainly good, but this is no Raptor; the ride is quite a bit firmer than Ford’s big Baja basher. Part of that comes from less suspension travel and some from the relatively small tires that are left aired-up to street pressures. Still, the Bison is up to the job — especially when it was time to slow way down and hit the toughest obstacles.
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